Return tubular superheater boiler



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J PRIMROSE RETURN TUBULAR SUPERHEATER BOILER Filed Jan. 29, 1925 TOR/Vgy Aug. 28, 1928. 1,681,952

J. PRIMROSE RETURN TUBULAR SUPERHEATER BOILER Filed Jan. 29, 1925 2 Sheets-Sheet 2 A TTORNEY Patented. Aug. 28, 1928.

UNITED STATES 1,681,952 PATENT OFFICE.

JOHN PBIMROSE OF RICHMOND, NEW YORK, ASSIGNOR, TO FOSTER WHEELER COR- PORATION, OF NEW YORK, N. Y.,

A conrom'rrou or new Yoax.

RETURN TUBULAR SUPERHEATER BOILER.

Application filed January 29, 1923. Serial No. 615,638.

The general object of, my invention is to provide a boiler furnace of the return tubular type with a superheater so arranged and disposed as to obtain the desired superheating effect, with a superheater which is simple, ef-

fective, accessible, and relatively inexpensive in construction; and which is so disposed as to minimize the construction and maintenance cost of the furnace housing. These results I secure, in accordance with the present invention, by utilizing a superheater of the radiant heat type, as a roof for the portion of the furnace chamber at the rear of the boiler proper.

The various features of novelty which characterize my invention are pointed out with particularity in the claims annexed to and forming a part of this specification, but for a better understanding of the invention, its

advantages and specific objects attained with its use, reference should be had to the accompanying drawings and descriptive matter in which I have illustrated and described preferred embodiments of my invention.

Of the drawings:

Fig. 1 is an elevation, in section on the line 1-1 of Fig. 3;

Fig. 2 is a view taken similarly to Fig. 1, but on a larger scale, and showing a portion only of the apparatus shown in Fig. 1;

Fig.3 is a section on the line 3-3 of Fig. 1;

Fig. 4 is a partial section on the line 4+4 of Fig. 5; and

Fig. 5 is a view taken similarly to Fig 3 illustrating a portion of a modified construction. i

In the drawings, and referring first to the construct-ion shown in Figs. '1, 2 and 3, A represents boiler of the horizontal return tubular type, and B and B represent the masonry side and rear end walls, respectively, of the furnace housing which encloses the combustion chamber space C beneath the boiler A proper, and the portion C of the furnace chamber at the rear of the boiler, through which the products of combustion and burning gases pass from the combustion space beneath the boiler into the boiler flues A. The

. boiler proper may be suspended, or may be supported by the boiler housing in any usual or suitable manner. The boilers shown in Figs. 1, 2 and 3 may be heated by the combustion of coal on a grate, or by the combustion of oil or gas, and as shown, was designed for the combustio f il, but I have not thought it necessary to show the oil burners and supply provisions, as my invention is not concerned with the character of fuel burned, orwith the provislons made for its combustion.

The roof of the chamber portion C is formed in large part by a superheater D.

The superheater D comprises superheater tubes D proper, each having a horizontal body portion terminating at one end in a bent upturned portion D connected to the superheater inlet header D At its opposite end, each superheater tube D is connected to the superheater outlet headers D. The body portion of each tube D is surrounded by a tubular casing formed of cast iron sections D which may be shrunk on the tubes, and have vertical sides and horizontal under surfaces. The tubes D and casing sections D are so relatively proportioned and spaced that the various sections D form a Sectional wall or roof, the under surface of which is hori-' zontal. The body portions of the tubes D are prevented from warping or bending under the changing temperature conditions to which they are subjected by stiffening members in the form of angle bars E arranged, one above each tube D, and bolted or otherwise secured to the casing sections D on the corresponding tube D, at suitable intervals D along the length of the tube. The superheater proper is covered by a suitable heat insulating material G, such as the mo tar like material known as plastic asbestos, hich preferably not only restricts heat loss by radiation from the top of the superheater, but serves as a packing or casing to prevent air and gas leak age through the joints in the superheater structure. As shown, the boiler proper has its upper side covered by heat insulating material G.

The superheater, as a whole, is supporte from the side walls B of the furnace housing,

through the superheater headers D and D which are preferably anchored in place on those side walls. In the particular construction illustrated, each header is supported adjacent its ends, by a saddle or bearing block H which rests upon the corresponding side wall B and is secured to the latter by anchor bolts I. Preferably each saddle block or bearing member H is provided with apertured earsto receive the ends of a yoke J for clamping the header in place. While the end tube casing sections 1) are shown as the superheater replaces the arched roof for the furnace chamber portion C of the as in close contact with the housing side Walls B, the weight of the superheater tubes and casings is intended to be wholly carried by the headers D and D. With the superheater tubes D and casings D suspended from the headers D and D, the elongation and contraction of the body portions of the tubes, resulting from their changes in temperature are accommodated by flexure of the end portions D and may occur without liability of damage to the superheater or depth of the furnace chamber portion C" and the rear Wall of the furnace housing is corbelled, as indicated at B to close the space between the rear edge of the superheater and the inner surface of the wall D. In many cases, however, the superheater may be of the samewidth, or of even greater width than the depth of the furnace portion chamber C, as shown in Fig. 4.

With the described arrangement shown in Figs. 1, 2 and 3, the superheater receives heat by radiation from the adjacent inner surfaces of the furnace walls, and in addition receives heat by contact with, and radiation from the heating gases. The heat absorbing capacity of a superheater thus constructed and located, is sufiicient to obtain any superheating effect ordinarily desired in practice, with a superheater which is durable, relatively small in bulk, comparatively inexpensive to construct, and is readily accessible for inspection and repairs when necessary. The fact that the superheater forms the roof of the furnace chamber portion G simplifies and cheapens the cost of construction of the boiler housing, and lowers the furnace housing maintenance cost, inasmuch ordinary return tubular boiler furnace which has been a relatively expensive portion of the boiler housing to construct, and has required frequent repairs and renewal because of its form and the severe temperature conditions to which it is subjected. The

superheater construction and arrangement not lonly reduces the maintenance cost of the p eliminating the necessity of repa ring. and renewing the roof formed by the superheater, but also because the superheater absorbs heat by radiation. from the adjacent side walls B, and from the and end wall B, and thereby cools and makes more durable, those portions of the furnace wall. Y

' Heretofore in a return tubular boiler provided with a superheater, the regular practice has been to arrange the superheater in the combustion chamber so that the superheater tubes are swept by the heating gases and receive heat mainly by convection and conduction. In comparison with such an arrangement, the present invention possesses advantages in addition to those already mentioned in that it does not obstruct any part of the combustion chamber, as do the tubes of a superheater disposed in the chamber, and consequently does not interfere with any desired disposition of the boiler blowofl' piping, and does not interfere with the ins ection, cleaning, or repair of the boiler an particularly of the boiler fines. With the present invention, moreover, it is much easier to keep the superheater clean than with the old arrangement, both because the new superheater is easier to clean, and also because soot and ashes accumulate on it much more slowly than they do on the superheater 1n the old arrangement. With the superheater forming a part of the furnace hous- Figs. 4 and 5, the superheater DA shown,

differs from the superheater D first described principally in that the superheater tubes 1) i are each provided with a bent upturned end portion D at each end, so that the inlet and outlet header D and D may be symmetrically disposed at the same level. While the tube end portions D are shown as passing through the upper portion of the side walls B of the furnace housing, the Weight of the superheater as a whole is carried through the headers D and D and suflicient clearance should be provided between the masonry and the tube end portions D, to accommodate the thermal elongation and contraction of the body portions of the superheater tubes. In Figs. 4 and 5, the inlet header D receives steam through the steam pipe FA connected to one end of the boiler AA.

While in accordance with the provisions of the statutes, I have illustrated and described the best forms of my invention now known to me, it will be apparent to those skilled in the art that some changes in form may be made without departing from the spirit of my invention as set forth in the appended claims, and that somefeatures of my invention may sometimes be used to advantage without a corresponding use of other features.

Having now described my invention, what I claim as new, and desire to secure by Letters Patent, is:

1. In a return tubular boiler furnace having masonry housing walls at the sides and rear end of the furnace chamber portion at the rear of the boiler, the improvement which consists in a superheater forming a roof for said chamber portion and comprising headers mounted on t housing Wa l at the sides of said chamber portion, and superheater elements connecting said headers and each comprising a body portion extending across said ehamber portion and a transverse end portion connecting the body portion to one of said headers.

2'. In a return tubular boiler furnace having housin Walls at the sides and rear end of the portlon of the furnace chamber at the rear of the boiler, the improvement Which consists in a superheater forming a roof for said chamber portion and comprising headers mounted on the housing wall at the sides of said chamber portion, and tubes each comprising a body portion extending across said chamber portion and up-turned end portion connected to said headers.

.3. In a return tubular boiler furnace having masonry housing Walls at the sides'and rear end of the portion of the furnace chamber at the rear of the boiler, the improyement which consists in a 'superheater forming a roof for said chamber portion and comprising headers mounted on the housing walls at the sides of said chamber portion, supertion to one of said headers and means each comprising a body portion extending across said chamber portion and a transverse end portion connecting the body ppror securing each of said headers in position on said wall comprising a bearing member mounted on said Wall and a yoke clamping the header in position on said bearing member.

4. In a return tubular boiler furnace having housing Walls at the sides and rear end of the portion of the furnace chamber at the rear of the boiler, the improvement which consists in a superheater forming a roof for said chamber portion and comprising headers mounted on the housing*wall at the sides of said chamber portion, and tubes each comprising a body portion extending across said chamber portion and having their extremities connected to said headers.

Signed at New York, in the county of New York and State of New York, this 26th day of January, A. D. 1923.

' JOHN PRIMROSE. 

